You have a wireless-enabled laptop, phone, and tablet. Each device needs to be assigned a unique “send” frequency and a unique “receive” frequency to communicate with a base station. Let S := {1, . ....

You have a wireless-enabled laptop, phone, and tablet. Each device needs to be assigned a unique “send” frequency and a unique “receive” frequency to communicate with a base station. Let S := {1, . . . , 8} denote send frequencies and R := {a, . . . , h} receive frequencies. A frequency assignment is an element of S × R. A set of frequency assignments is noninterfering if no elements of S or R appears twice. How many noninterfering frequency assignments are there for your three devices?